Added in Patch 1.11, obtaining it involves going into Naxxramas and completing a quest line. Since Naxxramas was moved to be floating above Dragonblight the staff is no longer obtainable since the components dropped in the original instance.

Encounter-limited weapons

A conjured sword, Andonisus is dropped by Atiesh, in the midst of the battle to purify the legendary staff Atiesh, at which point a player would wield it against the demon. It vanishes after 10 minutes, or if the wielder leaves Stratholme.

Items

A crystal that summons a Black Qiraji Battle Tank (fast bug mount). It's exactly like the red, green, yellow, and blue Battle Tanks that can be frequently found in the Temple of Ahn'Qiraj, but it can be used anywhere in the world, not just AQ40 like the others. A player must complete the extremely difficult Scepter of the Shifting Sands raid-based quest line and be the first to ring the Scarab Gong to open the gates of Ahn'Qiraj, or must ring it within 10 hours of the first player's ring (during the Ahn'Qiraj Invasion event). As the gates are now automatically opened on all new servers, this item is no longer obtainable.

In Wrath of the Lich King

Weapons

Val'anyr is a one-handed mace wielded by priests, druids, paladins, monks and shamans and is only available to those classes. Like Atiesh, the hammer is assembled from fragments. The 30 fragments of the weapon drop from bosses in Ulduar.

Unavailable

Not currently in the game. Blizzard mentioned that they would be adding it eventually, and clues exist in several quest lines, though with the events of Wrath of the Lich King this seems unlikely to be the case any longer.

First discovered in the World of Warcraft Official Armory, this appears to be the first, and only legendary fishing pole. It is believed to be a GM tool for testing new fishing system that was introduced in patch 3.1.

Shortly after this pole was publicly known it was removed from the Official Armory.